High Power Batteries (More than 5Ah)
Some batteries needto be "Bomb Proof"
For low powerapplications such as mobile phones or power tools where the typicalcost of a battery may be £10 or less, batteries are oftenconsidered as consumables and battery maintenance is not usually ahigh priority. But for high power Traction Applications such aselectric vehicles (EVs) and hybrid electric vehicles (HEVs) wherebatteries may cost thousands of pounds, maximising the Battery Lifebecomes a major design objective.
Batterydesigns may be optimised for capacity or forpower handling capability, often called "rate". For example, in EVapplications, range is most important and so they use high capacitybatteries. HEVs on the other hand require smaller batteries whichcan provide a high instantaneous power boost and they use high ratebatteries. The section on Cell Construction explains the designtrade-offs involved.
Deep cyclebatteries are designed to be discharged down to as much as 80%depth of discharge time after time, and have much thicker platesthat a standard automotive battery.
Many high powerbatteries are also used in safety critical applications or forproviding emergency power. The overriding design goal is that theyshould be able to deliver their specified power whenever they arecalled upon to do so. For this the user needs to be able to monitorthe condition of the battery (known as the State of Health) at anytime and to be have available tools and procedures to maintain thebattery in top working condition.
In manyapplications high power batteries also generate excessive heat andThermal Management also becomes a necessary design consideration.In the quest to get the maximum energy storage or maximum powerdelivery from practical battery installations many novel CellChemistries have been developed. These are almost always secondarycells, but some single use batteries have been developed foremergency or military applications.
Because of theirhigh energy content the consequences of failure of these cells canbe very dangerous. See the section on Safety for an indication ofthe destructive power of a shorted cell.
Safetyconsiderations should therefore be high on the designer's prioritylist.